Toddler Found In Trunk, Isaiah Theis, Likely Died From Heat; Wisconsin Toddler's Cause of Death 'Probable Hyperthermia' [PHOTO]

Isaiah Theis, the 2-year-old Wisconsin toddler who was found dead Thursday in the trunk of the car of a customer of his father’s car repair business, likely died from hyperthermia, according to the Polk County Sheriff’s Office.

Isaiah, 2, went missing Tuesday night and was found in the trunk by a Polk County sheriff’s deputy around 10:15 p.m. Wednesday, after the customer came to retrieve his car, CBS News reported.

The car had been checked as part of a search for the missing 2-year-old, but the trunk wasn’t inspected, according to Polk County Sheriff Peter Johnson.

On Friday, authorities said it was likely that Isaiah died from the heat. Preliminary autopsy reports showed the 2-year-old Wisconsin boy had no life-threatening injuries or bone fractures, according to the Associated Press.

The cause of death was listed as “probable hyperthermia,” but the manner of death was still under investigation Friday.

Johnson’s chief deputy, Steve Moe, told a press conference Thursday that he declined to speculate how the child wound up in the trunk, but expressed regret that authorities didn’t find his body sooner.

"Would we [have] liked to have forced entry to the car? Yeah, from my personal perspective," Moe said, according to CBS.

Moe said it was believed that the 2-year-old wandered from his home in Centuria, Wisc., adding that the toddler had a tendency to act that way, the Associated Press reported. He said all of the customers’ cars were locked.

Isaiah’s maternal grandfather, Paul Krey, told KARE that the car that Isaiah’s body was found in was parked on his son’s property and was waiting to be fixed. He also said that Isaiah’s mother was hospitalized due to stress caused by her son’s death.

The case of the missing child captured the hearts of volunteers in Centuria and beyond. More than 2,000 people participated in the search for the missing boy.